Temperature Guage

[sgr60]

My temperature gauge isn't working, so I went to the engine compartment to check and see if I could find where the sensor is.

I was a little confused by what I found.

In the photo below you can see a black wire going into a bolt on the manifold, I would think that this is the temp sensor, but it's connected to a black wire that leads to the AC compressor, as opposed to back to the firewall.

Maybe this is related, there is a green wire going back to the firewall, but it's connected to something I can't idenitfy - I've circled that in blue. It's bolted to the carb, but doesn't look like it's connected to anything. Any idea on what this is?

Thanks.